Vulnerability · Published Nov 2, 2026 · Assigned by certcc
CVE-2026-120596CVE-2026-120596
High 7.5
In plain English
A high-severity infinite loop in Nut/Net TCP/IP Stack from Ethernut / egnite GmbH. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities).
Official description
A remotely exploitable denial-of-service vulnerability exists in the TCP options parser of the Nut/Net TCP/IP stack included in Nut/OS, developed by Ethernut/Egnite. Nut/OS releases up to version 5.1 are affected. An unauthenticated attacker can send a single TCP segment containing an unknown TCP option with a length byte of zero to any open TCP port on a vulnerable device. When processed, this malformed option triggers an infinite loop in the function NutTcpInputOptions, permanently blocking the TCP processing thread and rendering all TCP-based services unresponsive until the device is rebooted.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Ethernut / egnite GmbH | Nut/Net TCP/IP Stack | Nut/OS 5.1 |
Weakness: CWE-835 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H